Circuit breaker toggle mechanism with spring-biased latch plate

ABSTRACT

A circuit breaker operating mechanism which may be set to constrain movable contacts to close with stationary contacts, but which is adapted to collapse resulting in the contacts opening. The operating mechanism comprises a toggle-link and a latch-frame articulated with one another so as to permit collapsing of the operating mechanism and a latch which may be disengaged to permit the collapsing. The invention provides in addition a latch-plate in the operating mechanism which by virtue of a lever advantage reduces the energy requirements to disengage the latch and so permits a more sensitive operating mechanism. The components are shaped to minimize space taken by the mechanism in its collapsed state.

United States Patent [191 Marot et al.

[111 3,754,108 Aug. 21,1973

[ CIRCUIT BREAKER TOGGLE MECHANISM WITH SPRING-BIASED LATCH PLATE [75Inventors: Maurice Rene Marot, Edenvale;

Norman William Povey, Ger'miston, both of South Africa [73] Assignee:Electrical Protection Co. (PTY) Ltd.,

Benoni, Transvaal, South Africa [22] Filed: Sept. 10, 1971 [21] Appl.No.: 179,306

[52] US. Cl 200/153 G, 335/21, 335/165, 335/167 [51] Int. Cl. H01h 3/46,HOlh 71/12 [58] Field of Search 200/153 G; 335/170,

[56] References Cited UNITED STATES PATENTS 3,544,931 12/1970 Patel335/174 3,251,232 5/1966 Harper 335/174X FOREIGN PATENTS OR APPLICATIONS974,284 11/1960 Germany 200/153 G Primary Examiner-J. V. Truhe AssistantExaminer-Robert A. Vanderhye Attorney-Fred Wiviott et al.

[57] ABSTRACT A circuit breaker operating mechanism which may be I setto constrain movable contacts to close with stationary contacts, butwhich is adapted to collapse resulting in the contacts opening. Theoperating mechanism comprises a toggle-link and a latch-framearticulated with one another so as to permit collapsing of the operatingmechanism and a latch which may be disengaged to permit the collapsing.The invention provides in addition a latch-plate in the operatingmechanism which by virtue of a lever advantage reduces the energyrequirements to disengage the latch and so permits a more sensitiveoperating mechanism. The components are shaped to minimize space takenby the mechanism in its collapsed state.

5 Claims, 9 Drawing Figures Patented Aug. 21, 1973 4 Sheets-Sheet lPatented Aug. 21, 1973 4 Sheets-Sheet 2 FIGS.

' FIG.4.

Patented Aug. 21, 1973 4 Sheets-Sheet 3 FIG.7.

Patented Aug. 21, 1973 4 Sheets-Shut, 4,

FIGS.

CIRCUIT BREAKER TOG'GLE MECHANISM WITH SPRING-IIIASED LATCH PLATEBACKGROUND OF THE INVENTION This invention concerns improvementsrelating to circuit breakers, for example moulded case circuit breakers.More particularly this invention concerns an operating mechanism incircuit breakers.

Circuit breakers, more particularly moulded case circuit breakers areknown which comprise an operating mechanism" settable to an on" positionin which it constrains contacts on a movable contact carrier to beclosed with complementary fixed contacts. Conversely the contacts areopened on return of the operating mechanism away from the on position.Circuit breakers are furthermore known in which such an operatingmechanism'is collapsible in its length between pivotal connections byarticulation of two main parts of the operating mechanism, a latch-frameand a togglelink, on disengaging a latch of the operating mechanism.This collapsing of the operating mechanism opens the contacts even whenthe operating mechanism is in the on position. When the operatingmechanism latch is engaged again the contacts are closed again,providing the operating mechanism. remains in the' on position.

Former circuit breakers which employed this type of operating mechanismused an electro-mechanical transducer, usually in the form of a small"solenoid, to supply the necessary energy to disengage the latch. Areduction of the energy required to disengage the latch would permitreduction or elimination of the amplification of the electrical signalused to initiate disengaging of the latch. Thus the" energy requirementfor disengaging the latch is important.

One object of this invention is to provide a latch mechanism which maybe used to reduce the quantity of energy needed to disengage the latch.Afurther or subsidiary object of this invention is to provide such alatch mechanism which at least in preferred embodiments may occupy aminimum space in the unlatched position as well as the latched positionand with the operating mechanism in the collapsed position as well asthe uncollapsed position.

BRIEF SUMMARY OF THE INVENTION A circuit breaker in accordance with thisinvention comprises an operating mechanism settable to an on position inwhich it may constrain contacts on a movable contact carrier to beclosed, the operating mecha. nism being collapsible by articulation of atoggle-link and a latch-frame after disengagement of a latch, in whichthe operating mechanism comprises a latch-plate adapted to restrain thelatch-frame and toggle-link against articulation only while thelatch-plate is itself restrained byengagement of the latch.

- Conveniently a catch and a lever of the latch are mounted on thelatch-frame, so that the catch may engage an edge of the latch-plateduring engagement of the latch, and the catch disengage the edge duringdisengagement of the latch.

In accordance with a preferred embodiment of this invention thetoggle-link comprises a curved sliding face terminating in a restrainingregion and the latchplate comprises a coacting formation adapted toengage with the restraining region when the latch-plate is to restrainthe toggle-link against articulation and to slide against the slidingface when the latch-plate is to release the toggle-link to articulatewith the latch frame. t

Preferably the sliding face is juxtaposed substantially overlapping thelatch-frame when the toggle-link is in a position in which it isrestrained by the latch-plate, and the toggle-link and latch-frame areinthe uncollapsed position.

Preferably the curved sliding face of the toggle-link is shaped so as toextend from a position near the latchframe in a direction opposite tothe direction of movement of the latch-frame and toggle-link onarticulating towards the collapsed position.

Preferably a toggle-link portion which carries the I sliding face isshaped to minimize the distance of projection of that portion beyond theoperating member when it is in the collapsed position.

Preferably the toggle-link extends from its main portion on beyond apivot by means of which it is articulated to the latch-frame andterminates in a restraining region adapted to restrain the latch-plateon a coacting formation of the latch-plate, the said coacting formationlocated at a radial distance from an axis of pivotal connection of thelatch-plate to the latch-frame which is less than the radial distancefrom an edge of the latch-plate engaged by a catch of the latch to theaxis of pivotal connection of the latch-plate to the latchframe.

a In accordance with another aspect of this invention a collapsibleoperating mechanism, for a circuit breaker, having a toggle-linkarticulated to a latchframe and a latch, comprises a latch-plate adaptedto restrain the toggle-link and latch-frame against articulation onlywhile'the latch-plate is itself restrained by engagement of the latch.

This invention will be more fully described by way of example, withreference to the drawings.

BRIEF DESCRIPTION OF DRAWINGS In the drawings;

FIG. 1 is a schematic illustration of a circuit breaker of which theoperating mechanism is illustrated in subsequent figures in more detail,

FIG. 2 is a schematic illustration of the operating mechanism shown inFIG. 1,

FIG. 3 is a similar illustration of the operating mechanism shown inFIG. 2 but in the collapsed condition,

FIG. 4 is a front view of an operating mechanism in accordance with thepreferred embodiment of this invention, I

FIG. 5 is a side view of the operating mechanism shown i'n FIG. 4,on'view V- -V of FIG. IV, I

FIGS. and 7 are side sectional views of the operating mechanism shown inFIGS. 3 and-4'on sections Vl-VI and VII-VII respectively,

FIG. 8 is a side view-of the operating mechanism shown in FIGS. 4 to 7but in the collapsed condition, and

FIG. 9 is a side view of a moulded case circuit breaker incorporatingthe operating mechanism shown in FIGS. 4 to 8, on a smaller scale.

DESCRIPTION OF THE PREFERRED EMBODIMENTS.

As indicated in FIG. 1 the main functionalparts of a circuit breakercomprise the following: an operating mechanism 1, pivotally connectedbetween a toggle 2 and a movable contact carrier 3, by pivots 4 and 5respectively, contact carrier 3 being pivotally mounted by pivot 6 inthe case 7, and toggle 2 being pivotally mounted by pivot 8 in the case7. Contact carrier 3 carries contacts 9 here shown contacting contacts10 fixed in the case 7, toggle 2 being in a position in which theoperating mechanism 1 is in the on position. Broken lines 11 indicatethe positions of the movable components if the operating mechanism 1 iscollapsed. The operating mechanism 1 is articulated by pivot 12 for thepurpose of collapsing as shown.

As shown in FIG. 2 the operating mechanism 1 comprises a toggle-link l3articulated to a latch-frame 14 by pivot pin 12. The latch-frame 14carries a latch comprising catch 15 in the form of a shaft having a flatground on it and a lever 16, the catch 15 being operable by the lever 6.The operating mechanism further comprises a latch-plate 17 which has anedge 24 which is engaged by the catch 15 as shown. Latch-plate 17carries a pin 18 which formation restrains the togglelink 13 againstarticulation so that the operating mechanism I cannot collapse. Thetoggle-link has a curved sliding face 19 terminating in a restrainingregion 20 engaged by the pin 18 of the latch-plate 17 in the uncollapsedcondition. It will be noted that the pivot pin 12 articulating thetoggle-link 13 and latch frame 5 is eccentric of a straight line 21joining the centres of the pivot pins 4 and 5 which are used topivotally connect the operating mechanism 1 to toggle 2 and contactcarrier 3, (see FIG. 1), respectively. This eccentricity biasses theoperating mechanism to collapse when a compressive force is applied tothe operating mechanism by carrier 3 and toggle 2. In these sketchesbiassing springs for additional biassing are not shown as it will beclear to those skilled in the art where these are necessary ordesirable.

When the lever 16 is moved in the direction of arrow 22 the catch 15, inthe form of a shaft with a flat ground on it rotates until the flatcoincides with the edge 24 of the latch-plate l7 and this releases thelatch-plate 17. Under action of the bias the latch-plate l7 pivots onpivot pin 5 in the direction of arrow 23 and this releases thetoggle-link 13 to articulate with the latch-frame 14 and theoperating-member l collapses, the various components attaining thepositions shown in FIG. 3.

In FIGS. 4 to 9 the operating mechanism and circuit breaker comprise thefunctionally identical components, the shapes being only somewhatdifi'erent, and so the same reference numerals are used throughout thesefigures as are used in FIGS. 1 to 3, for corresponding features. Themechanism operates in the same way as that shown in FIGS. 1 to 3 and thedescription with reference to those figures can be read with referenceto FIGS. 4 to 8. Biassing springs 25 and 26 are additionally shown inthese figures, however. Spring 25 biases the latch-plate 17 in theopposite direction to that indicated by arrow 23 and spring 26 biassesthe catch 15 in the opposite direction to that indicated by arrow 22.These figures also show a tag 27 bent at right angles to the latch-framel4 and acting as a stop to limit movement of the catch 15 as indicatedby the extreme positions of catch 15 in FIGS. 5 and 8. Also tag 28limits movement of the toggle-link 13 relative to the latchframe 14 fromwhich the tag is bent at right angles. In FIGS. 6 and 7 the flat 29 ofthe shaft formed catch l5 is visible. In FIG. 6 distances 30 and 31 fromthe axis of pin 5 to the axis of pin 18 and from the axis of pin amountof energy required to achieve unlatching. In an industriallymanufactured operating mechanism according to FIGS. 4 to 9 at one fourththe size of these figures, an energy consumption of 0.59 Newtonmillimeters was sufficient to disengage the catch 15 from the edge 24 ofthe latch-plate 17 while the operating mechanism 1 was loaded so thatits collapsing expended an energy of 147 Newton millimeters,approximately. This order of sensitivity was achieved while neverthelesshaving reliable operation with freedom from accidental unlatching, e.g.,from knocks or vibration of moderate intensity.

In FIG. 9 the movable contact carrier 3 is shown in the position inwhich contacts 9 and 10 are open, in contrast with FIG. 1 where they areclosed. Again corresponding parts are numbered with correspondingnumerals as in the previous figures.

What we claim is:

1. In a circuit breaker, an operating mechanism which comprises anoperating mechanism settable to an on position in which it may constraincontacts on a movable contact carrier to be closed, the operatingmechanism being collapsible by articulation of a toggle-link and alatch-frame after disengagement of a latch, in which the operatingmechanism comprises a latch plate adapted to restrain the latch-frameand toggle-link against articulation only while the latch-plate isitself restrained by engagement of the latch, in which the toggle-linkcomprises a curved sliding face terminating in a restraining region andthe latch-plate comprises a coacting formation which engages therestraining region when the latch-plate is to restrain the togglelinkagainst articulation and which engages the sliding face when thelatch-plate is to release the toggle-link to articulate with thelatch-frame, and which comprises a biassing spring which biasses thelatch-plate relative to the latch-frame with a torque in opposite senseto the direction of rotation of the latch-plate, when it is engaged withthe latch.

2. An operating mechanism according to claim 1, in which the slidingface is juxtaposed substantially overlapping the latch-frame when thetoggle-link is in a position in which it is restrained by thelatch-plate, and the toggle-link and latch-frame are in the uncollapsedposition.

3. An operating mechanism according to claim 1, in which the curvedsliding face of the toggle-link is shaped so as to extend from aposition near the latchframe in a direction opposite to the direction ofmovement of the latch-frame and toggle-link on articulating towardsthecollapsed position. i

4. An operating mechanism according to claim 1, in which the toggle-linkextends from its main portion on beyond a pivot by means of which it isarticulated to the latch-frame and terminates in a restraining regionadapted to restrain the latch-plate on a coacting formation of thelatch-plate, the said coacting formation located at a radial distancefrom an axis of pivotal connection of the latch-plate to the latch framewhich is less than the radial distance from an edge of the latchplateengaged by a catch of the latch to theaxis of pivotal connection of thelatch-plate to the latch-frame.

5. A circuit breaker operating mechanism having a movable contactcarrier for opening and closing the circuit breaker contacts and alinkage pivotally connected to the carrier and having a rigid conditionfor holding said contact carrier in a closed position and being biasedto a collapsed condition wherein said carrier is permitted to move to anopen position, said linkage comprising:

a first collapsible member pivotally connected to the contact carrier,

a second collapsible member pivotally connected to said firstcollapsible member for relative movement between rigid and collapsedpositions,

said second member having a curved face formed thereon and a restrainingregion,

latch means pivotally mounted on said first member and includingrestraining means,

said restraining means being engageable by said restraining region toprevent movement of said second member out of its rigid position whensaid latch means is in a first position, said restraining means movingout of engagement with said restraining region when said latch-means'ismoved from said first position to a second position to permit saidsecond member to move to its collapsed position,

catch means movably mounted on said first member for engaging said latchmeans to maintain it in said first position when said catch means is inone position, said catch means being movable to a second position todisengage said latch means whereby said latch means may be moved to saidsecond position,

the engagement between said second member and said latch means acting tourge said latch means into frictional engagement with said catch means,

spring means engaging said latch means for biasing the same away fromsaid catch means to minimize said frictional engagement to reduce thetripping force necessary to move said catch means to its secondposition,

said restraining means engaging said curved surface when said latchmember is released from said catch means to limit movement of said catchmeans under the influence of said spring means.

1. In a circuit breaker, an operating mechanism which comprises anoperating mechanism settable to an ''''on'''' position in which it mayconstrain contacts on a movable contact carrier to be closed, theoperating mechanism being collapsible by articulation of a toggle-linkand a latch-frame after disengagement of a latch, in which the operatingmechanism comprises a latch plate adapted to restrain the latch-frameand toggle-link against articulation only while the latch-plate isitself restrained by engagement of the latch, in which the toggle-linkcomprises a curved sliding face terminating in a restraining region andthe latch-plate comprises a coacting formation which engages therestraining region when the latch-plate is to restrain the toggle-linkagainst articulation and which engages the sliding face when thelatch-plate is to release the toggle-link to articulate with thelatch-frame, and which comprises a biassing spring which biasses thelatch-plate relative to the latch-frame with a torque in opposite senseto the direction of rotation of the latch-plate, when it is engaged withthe latch.
 2. An operating mechanism according to claim 1, in which thesliding face is juxtaposed substantially overlapping the latch-framewhen the toggle-link is in a position in which it is restrained by thelatch-plate, and the toggle-link and latch-frame are in the uncollapsedposition.
 3. An operating mechanism according to claim 1, in which thecurved sliding face of the toggle-link is shaped so as to extend from aposition near the latch-frame in a direction opposite to the directionof movement of the latch-frame and toggle-link on articulating towardsthe collapsed position.
 4. An operating mechanism according to claim 1,in which the toggle-link extends from its main portion on beyond a pivotby means of which it is articulated to the latch-frame and terminates ina restraining region adapted to restrain the latch-plate on a coactingformation of the latch-plate, the said coacting formation located at aradial distance from an axis of pivotal connection of the latch-plate tothe latch frame which is less than the radial distance from an edge ofthe latch-plate engaged by a catch of the latch to the axis of pivotalconnection of the latch-plate to the latch-frame.
 5. A circuit breakeroperating mechanism having a movable contact carrier for opening andclosing the circuit breaker contacts and a linkage pivotally connectedto the carrier and having a rigid condition for holding said contactcarrier in a closed position and being biased to a collapsed conditionwherein said carrier is permitted to move to an open position, saidlinkage comprising: a first collapsible member pivotally connected tothe contact carrier, a second collapsible member pivotally connected tosaid first collapsible member for relative movement between rigid andcollapsed positions, said second member having a curved face formedthereon and a restraining region, latch means pivotally mounted on saidfirst member and including restraining means, said restraining meansbeing engageable by said restraining region to prevent movement of saidsecond member out of its rigid position when said latch means is in afirst position, said restraining means moving out of engagement withsaid restraining region when said latch means is moved from said firstposition to a second position to permit said second member to move toits collapsed position, catch means movably mounted on said first memberfor engaging said latch means to maintain it in said first position whensaid catch means is in one position, said catch means being movable to asecond position to disengage said latch means whereby said latch meansmay be moved to said second position, the engagement between said secondmember and said latch means acting to urge said latch means intofrictional engagement with said catch means, spring means engaging saidlatch means for biasing the same away from said catch means to minimizesaid frictional engagement to reduce the tripping force necessary tomove said catch means to its second position, said restraining meansengaging said curved surface when said latch member is released fromsaid catch means to limit movement of said catch means under theinfluence of said spring means.